1,3,5-trihydroxy-2,4,6-benzene tricarboxylic acid and water soluble salts thereof

ABSTRACT

Novel compounds are provided which are 1,3,5-trihydroxy-2,4,6benzene tricarboxylic acid and salts thereof. These compounds are useful sequestering agents.

United States Patent 1151 3,699,159 Connor et al. 14 1 Oct. 17, 1972 l,3,5-TRIHYDROXY-2,4,6-BENZENE, Referemes ii TRICARBOXYLIC ACID AND WATER FOREIGN PATENTS OR APPLICATIONS 7 D f THEREOF 1,155,776 6/1969 016111 1311111111 [731 Assignee: The Procter & Gamble Compuny, [chit-o 51797 (1968) Cincinnati Ohio I Primary Examiner-Lorraine A. Weinberger [22] Filed: Dec. 28, 1970 Assistant Examiner-John F. Terapane [2]] App}. No; 102,049 Attorney-Julius P. Filcik and Charles R. Wilson [57] ABSTRACT v v {iii 2583iJJJiJJJJJJJffYTfff.533????1JE1332533 e compounds P1111111 w [58] Field of Search ..260/52l R, 501.11 mummy! and Salts thereof. These compounds are useful sequestering agents.

4 Claims, No Drnwings,

l ,3 ,5 -TRII-IYDROXY-2,4,6-BENZENE TRICARBOXYLIC ACID AND WATER SOLUBLE SALTS THEREOF BACKGROUND OF THE INVENTION The role of sequestering agents in softening water, i.e.,- in sequestering or complexing the hardness minerals in water supplies, is well known. Sequestering agents are recognized aids in detergent processes because they tie-up calcium and magnesium ions which otherwise react with soaps and synthetic detergents to formsoap curds and adversely effect detergency and foaming properties of the detergents. Condensed polyphosphates such as tripolyphosphates and pyrophosphates are widely used as ingredients in detergent compositions, in part at least, because of their property of sequestering hardness ions. Such phosphorus containing compounds as well as nitrogen containing compounds, e.g., nitrilotriacetates, are highly effective. However, the effect of the phosphorous content and the nitrogen content of these sequestering agents upon eutrophication of lakes and streams is being questioned. Eutrophication is a natural aging process of lakes that depends upon supplies of nutrients for algae and other plant life which in turn serve as food for fish. Excessive or accelerated eutrophication is caused by an over abundance of nutrients. Phosphorus and nitrogen are such nutrients. These materials are not per se responsible for eutrophication since other material such as a carbon supply is essential.

These circumstances have developed a need for phosphorus-free and nitrogen-free sequestering agents.

' The object of the present invention is to provide such a class of compounds which are useful as sequestering agents, especially when used as builders in conjunction with water soluble organic synthetic detergents.

DESCRIPTION OF THE INVENTION The present invention relates to a class of poly-functionally-substituted aromatic sequestering compounds.

These compounds are l,3,5-trihydroxy-2,4,6- benzene tricarboxylic acid and water soluble salts thereof. The cations forming water soluble salts are alkali metals such assodium, potassium, and lithium, and ammonium and alkyl substituted ammonium, e.g., triethanol ammonium.

The process by which these novel compounds are prepared forms no part of the present invention. Any convenient synthesis can be used. The following examples are illustrative of satisfactory methods.

EXAMPLE I Preparation of l,3,5-trihydroxy-2,4,6-tricarboxy benzene One hundred grams of Na -l,3,5-trihydroxy-2,4,6- benzene trisulfonate, 600 mls. of distilled water, 100 grams of sodium acetate and a few drops of acetic acid are added to a stirred reaction vessel. To this, 100 grams of bromine is added dropwise. This mixture is agitated and held at 0 C. for 2 hours. The precipitate, l,3,5-trihydroxy-2,4,6-tribromobenzene, is then filtered out and freeze dried. Thirty grams of this dried material are slurried into 200 mls. of ethyl ether. Fifty mls. of this slurry, 15 grams of magnesium tumings, and

200 mls. of ethyl ether are charged into a three-neck reaction vessel and heated to reflux. After adding one gram of iodine crystals, the remainder of the slurry is added slowly. An additional gram of iodine crystals is.

added when about half of the slurry has been added to the reaction mass. The mixture is agitated at reflux for 6 hours then allowed to stand for 2 days. After separating out all residual magnesium tumings, the remaining material is placed in an agitated reaction flask and 2 pounds of dry ice are added slowly. The slurry containing l,3,5-trihydroxy-2,4,6-benzene tricarboxylic acid is then filtered and neutralized with 10 percent NaOl-I to yield the sodium salt.

EXAMPLE II V Preparation of l,3,5-trihydroxy-2,4,6-benzene tricarboxylic acid C. The solution is cooled again to 0 C. and one-half mole of the 1,3,5-trihydroxy-2,4,6-triacetylbenzene is added. This reaction mass is stirred at room temperatricarboxylic acid formed is readily recovered.

SEQUESTRATION EVALUATION PROCEDURE The sequestering properties of the novel class of sequestrants of this inventionare demonstrated with the following procedure.

The evaluations are run in 200 ml. beakers at 23 3 C. with a magnetic stirrer. 50 ml. 14 grain/gal. (calculated as CaCO CaCl solution is poured into the beaker. The requisite amount of sequestering agent (builder) sample to give a final solution concentration of 0.06 percent, 0.03 percent, or 0.02 percent, is weighed or pipetted into the beaker. The sampleis brought to pH 7 with KOH or HCl as needed. Distilled water is added to give a total volume of I 3 ml. Fine adjustment is made to pH 7.00 t 0.05 with a Corning Model 12 meter and Corning Model 476022 glass electrode. At this point the calcium ion electrode is plugged in place of the pH electrode and the calcium ion activity is measured. The expanded scales either 0 to +100 or 0 to l00 millivolts, as necessary, are used. All readings are made with slow stirring. The resultant millivolt reading is converted into grains/gal. using a standardization curve. This amount represents residual hardness. The standards, 100, 10, 7, 5, 3, 1, 0.5 and 0.1 grains/gal. (as CaCO CaCl at pH 7.00 are linear with potential down to l grain/gal. and by 0.1 grain/gal. (1.7 X 10' molar) the practical limit of measurement has been reached. Day-to-day variation in potential readings is appreciable above 1 grain/gal; it amounts to i 3 millivolts or i 10 percent. Below 1 grain/gal. error grows rapidly; however, precise statements of error limits are meaningless. A day-to-day variation in the behavior of even good calcium electrodes is to be expected below I grain/gal. At times, linearity will extend almost to 0.1 grain/gal. and then the best error limits will obtain. A further clue to superb calcium electrode performance is the rate at which it comes to its final potential. At best, this will be on the order of a second; about seconds is the usual time. In summary, readings to within 10 percent can always be made down to 1 grain/gal. With a superb electrode, this can be extended to 0.1 grain/gal.

The sequestering agents of this invention have special usefulness when used in conjunction with water soluble organic synthetic detergents. This preferred embodiment is the subject of a separate, concurrentlyfiled application Ser. No. 102,159 for patent titled A DETERGENT COMPOSITION CONTAINING POLYFUNCTIONALLY-SUBSTITUTED ARO- MATIC ACID SEQUESTERING AGENT with Daniel S. Connor and Harry Karl Krummel as inventors.

The foregoing description and examples describe and illustrate certain operable and preferred embodiments of the present invention. It is not intended that the invention should be so limited since. variations and modifications thereof will be obvious to those skilled in the art, all of which are within the spirit and scope of this invention.

What is claimed is:

l. l,3,5-trihydroXy-2,4,6-benzene tricarboxylic acid.

2. The water-soluble salt of l,3,5-trihydroxy-2,4,6- benzene tricarboxylic acid wherein the cation of said salt is selected from the group consisting of alkali metal, ammonium and triethanol ammonium.

3. The alkali metal salt of l,3,5-trihydroxy-2,4,6- benzene tricarboxylic acid.

4. Sodium-l ,3,5-trihydroxy-2,4,6-benzene tricarboxylate. 

2. The water-soluble salt of 1,3,5-trihydroxy-2,4,6-benzene tricarboxylic acid wherein the cation of said salt is selected from the group consisting of alkali metal, ammonium and triethanol ammonium.
 3. The alkali metal salt of 1,3,5-trihydroxy-2,4,6-benzene tricarboxylic acid.
 4. Sodium-1,3,5-trihydroxy-2,4,6-benzene tricarboxylate. 